A Saudi detainee at the US prison in Guantanamo Bay has pleaded guilty to terrorism charges in connection with the 2002 suicide bombing of a French oil tanker off Yemen.
Ahmed Mohammed Ahmed Haza al-Darbi, the brother-in-law of one of the 9/11 plane hijackers, admitted planning, aiding and supporting an attack on the MV Limburg which killed a Bulgarian sailor, injured a dozen and caused a large oil spill in the Gulf of Aden.
Darbi - who has been held at the camp in Cuba for more than a decade - likely faces up to 15 more years in prison, the chief prosecutor, Army Brigadier General Mark Martins, said.
Some of that time could be served in his native Saudi Arabia.
Wearing a white button-down shirt and a fluorescent yellow tie and headphones carrying simultaneous Arabic translation, the stout Saudi with a sparse beard admitted being an "alien unprivileged enemy belligerent".
His lawyer, Ramzi Kassem, announced his client was pleading guilty to charges of terrorism and to attacking civilians and civilian targets before the US military judge at Guantanamo.
"This moment is bittersweet," said Kassem, whose client agreed to co-operate with prosecutors as part of the plea deal.
They accuse Darbi of meeting and working for fellow Saudi Guantanamo detainee Abd al-Rahim al-Nashiri, who faces the death penalty on charges he masterminded the Limburg attack and the 2000 attack against the USS Cole in Yemen that left 17 dead. By pleading guilty, Darbi, 39, could become a key witness against Nashiri, whose trial is likely to open in September.
Darbi "has pledged to be law-abiding and to co-operate fully and truthfully with authorities", Martins said, adding that soon after his arrest, Darbi began "divulging some useful information to authorities about his involvement in terrorist activities".
Darbi admitted supplying visas, boats and other necessary equipment to those who carried out the attack on the Limburg.
Under the terms of the plea deal, Darbi will not be officially sentenced for at least three years, judge Mark Allred said at the hearing, which was retransmitted for reporters at the US military base in Fort Meade, Maryland, outside Washington.
The delay means he would still be at the US prison in Cuba when Nashiri's trial begins.
Martins said that once Darbi was formally sentenced, he could be released from Guantanamo to serve the rest of his sentence in Saudi Arabia.